The evaluation will continue of the biological activities of a series of analogues of acetyl seco-hemicholinium No. 3 (Ac seco-HC-3), a compound known to inhibit choline acetyltransferase both in vitro and in vivo. The analogues will be evaluated for their toxicity in mice, neuromuscular and cardiovascular activities in rabbits, acetyl and butyryl cholinesterase inhibitory activities in vitro, mouse brain mince inhibition of synthesis of acetylcholine and inhibitory activity against mouse brain choline acetyltransferase. One series of analogs of Ac-seco-HC-3 will have a phenyl ring removed from the central nucleus (the norphenyl series) and another series will have the central nucleus increased by one phenyl ring (the terphenyl series). These will be evaluated to determine their biological activities. All of the compounds will likewise be exposed to tissue slices and then evaluated for localization by fluorescence microscopy.